Optimizing dispersion techniques for enhanced electrical and piezoresistive properties in cement composites with carbon fibers, multi-walled carbon nanotubes, and nano nickel powder

The dispersion techniques used for conductive materials in cement matrices significantly influence the piezoresistive sensitivity of smart concrete. Consequently, researchers have explored various methods to enhance the sensing efficiency of concrete structures. Micro and nanomaterials, including carbon fibers (CF), multi-walled carbon nanotubes (MWCNT), and nano nickel powder (NNi), have been utilized to produce smart concrete. This study presents an in-depth analysis of various dispersion techniques reported in the literature, aiming to identify the most effective method for each material. The evaluation of each mixing technique was based on electrical resistivity (ER), piezoresistive properties, and compressive strength of conductive cement composites. The content of conductive materials was fixed at 0.5% by volume in all mixes to assess the relative effectiveness of the dispersion methods. ER was investigated using a two-electrode method. The findings indicate that CF, when mixed using a dry mixing method, achieved superior dispersion compared to other techniques. The ER of CF composites decreased by up to 99% compared to plain cement composites after 28 d. For MWCNT, mechanical mixing with water and a superplasticizer provided better dispersion than ultrasonic mixing, with a reduction in ER of up to 89% compared to other methods. Appreciable dispersion of NNi was achieved by directly adding NNi powders to the fresh cement mixture. However, the ER reduction for NNi composites was relatively low at approximately 28%, compared to CF and MWCNT composites. The dispersion methods that improved ER also demonstrated excellent piezoresistive sensitivity for all materials. However, enhancing the electrical properties through improved dispersion methods did not necessarily lead to better compressive strength outcomes. Compressive strength tests were conducted for all dispersion methods, and the results underline the trade-off between electrical performance and mechanical properties in conductive cement composites.

Journal

FRONTIERS OF STRUCTURAL AND CIVIL ENGINEERING

Year

2025

Volume

19

Issue

12

Pages

2137-2154

ISSN

2095-2430

eISSN

2095-2449

DOI

10.1007/s11709-025-1254-8

WoS UID

WOS:001641012200001